シーザー暗号(AOJ0017)

caesar.py

#!/usr/bin/env python2
# coding: utf-8

def caesar(s, n):
    d = {}
    for c in (65, 97):
        for i in range(26):
            d[chr(i+c)] = chr((i+n) % 26 + c)

    return "".join([d.get(c, c) for c in s])


while True:
    try:
        encrypt_txt = raw_input()
    except EOFError:
        break

    for i in range(26):
        t = caesar(encrypt_txt, i)
        if  "the" in t or "this" in t or "that" in t:
            print t
            break